The present invention generally relates to an impact absorbing composite. More specifically, the present invention relates to an impact absorbing composite that is formed of separate, discrete, and independent impact absorbing members. The impact absorbing composite is capable of conforming to complex three-dimensional surfaces. Also, the impact absorbing composite is capable of both absorbing and dissipating energy from an impact that is applied against the impact absorbing composite. The present invention further relates to a method of making the impact absorbing composite.
Enhanced participation in contact sports, such as football, soccer, and rugby, along with enhanced participation in other high impact energy activities, such as inline skating and white water kayaking, has fueled the demand and need for improved impact absorbing materials. These types of contact sports and high-impact activities often cause application of high energy impacts against discrete portions of the human body that often cause bruises and even more serious injuries, such as broken or fractured bones.
Besides the noted contact sports and high energy impact activities, there are a number of other activities that, in the event of an accident or spill, may cause injury to the body. Until the past few years, participation in these activities, such as bicycle riding, was not considered to be an activity requiring much protective equipment. Now, however, bicycle riders of all ages are routinely advised to wear a protective bicycle helmet. Also, over the past few years, there has been a tremendous growth in off-road activities, such as mountain biking, motocross on both bicycles and motorcycles, and all terrain vehicle (ATV) usage on off-road trails.
In addition to these activities there has been a tremendous rate of growth in other applications for impact absorbing materials. For example, there has been an enhanced focus upon making automobiles safer to both the driver and passengers during automobile crashes. Years ago, passenger compartments in automobiles routinely had unpadded, bare metal surfaces. While such bare unprotected surfaces have gradually disappeared from today's automobiles, there is still a continuing emphasis upon making both interior automobile surfaces safer for the driver and passengers. Also, automobile manufacturers increasingly focus upon incorporating safer materials in automobile components that will help to absorb and dissipate impact energies that are created in automobile crashes.
Even in more mundane activities, such as walking, there has been an increased emphasis upon energy-absorbing surfaces and products for human beings. First, flooring manufacturers are developing new flooring materials that are more energy absorbent and more comfortable for pedestrians. Also, shoe manufacturers are increasingly marketing energy absorbing soles for shoe purchasers. Indeed, there is a large market demand for after market impact absorbing shoe inserts. Marketing of such shoe inserts is often targeted to participants in sports, such as basketball, football, soccer, and running, where repetitive impacts during each successive step may cause injuries to the foot and lower leg, such as sprains, shin splints, and even broken bones.
Due to the enhanced market for impact absorbing materials, great strides have been made toward reducing injuries generated by impacts that are applied against the human body. However, many of these new impact absorbing materials merely amount to laminates of multiple continuous layers. Continuous layers suffer from a couple of different problems, typically. For example, continuity of a layer will often inhibit the ability of adjacent layers to fully exhibit properties, such as elasticity, of the adjacent layers. For example, where a pair of layers are laminated together, and both layers have a certain degree of elasticity, the layer with the lower degree of elasticity will inhibit the layer with the higher degree of elasticity from fully exhibiting that higher degree of elasticity. Also, where one continuous layer is fairly rigid and an adjacent continuous layer is fairly flexible, the fairly rigid continuous layer will inhibit the ability of the flexible continuous layer to exhibit the flexibility.
The existing impact absorbing materials that are formed of continuous layers, only, necessarily must sacrifice some degree of impact absorbing capability. First, layer thicknesses must typically be minimized to prevent the impact absorbing material from becoming too heavy and bulky for consumer tastes. Also, to the degree that impact absorbance depends upon elevated rigidity in one of the continuous layers, existing impact absorbing materials consequently sacrifice flexibility and the ability to conform to complex three-dimensional shapes in favor of enhanced impact absorbance capability, or, alternatively, sacrifice impact absorbing capability in favor of enhanced flexibility and ability to conform to complex three-dimensional surfaces.
One reason that manufactures of impact absorbing materials have come to rely primarily upon continuous layers is that manufacture of impact absorbing materials with discontinuous layers has been traditionally considered to be technically impractical and expensive. With the increased degree of automation in manufacturing activities, manufacturers have typically focused upon manufacturing processes relying upon continuous webs of material that may be formed, laminated, and transported via efficient conveying systems. This has led many manufacturers of impact absorbing materials to focus upon manufacture of more technically complex and expensive continuous layers in search of improved material flexibility material impact absorbance. While such improvements have enhanced the knowledge base with regard to impact absorbing materials, these approaches have typically enhanced, sometimes dramatically, the cost of impact absorbing materials to the consumer, while still failing to uncouple the property interdependence existing between continuous layers in existing impact absorbing materials. Therefore, despite these industry developments, existing impact absorbing materials that are formed of multiple continuous layers continue to sacrifice flexibility and conformability in favor of impact absorbance, or continue to sacrifice impact absorbance in favor of flexibility and conformability.
As another example, impact absorbing products have been developed that incorporate a fluid within a polymeric envelope. When an impact is applied against one portion of the envelope, the fluid is displaced to a portion of the envelope located away from the impact point on the envelope. The envelope is typically made of a somewhat flexible polymeric material. The energy of the impact against the envelope is typically dissipated by generation of pressure in the fluid, with consequent expansion of the envelope. While such an impact absorbing material does, theoretically, have many benefits, practical considerations limit the actual capabilities of such a material. For example, the volume of fluid within the envelope must typically be limited due to the density of the fluid contained within the envelope and the consequent overall weight of the fluid-filled envelope. Such limitations of the envelope volume necessarily limit the thickness of the fluid layer within the envelope, which thereby detracts from the impact absorbing capabilities of the fluid-filled envelope.
While many enhancements have been developed and introduced to consumers of impact absorbing materials, these improved impact absorbing materials continue to suffer from a number of drawbacks. For example, technical improvements within individual continuous layers of existing impact absorbing materials have caused great increases in the costs of these impact absorbing materials to consumers. Also, continued industry reliance upon only continuous layers in some impact absorbing materials prevent these impact absorbing materials from fully exhibiting the flexibility characteristics of the more flexible continuous layer while also fully exhibiting the impact absorbing properties of the continuous layer that has the greater impact absorbing capability.
Thus, a need exists for an impact absorbing composite that exhibits both enhanced flexibility and conformability along with enhanced impact absorbing capabilities. Also, a need exists for an improved impact absorbing material that successfully couples a discontinuous impact absorbing layer with a flexible and conformable continuous layer. Furthermore, a need exists for a new method of manufacturing an impact absorbing material that exhibits both enhanced flexibility and conformability, along with enhanced impact absorbing properties. The impact absorbing composite of the present invention provides a solution to each of these difficult challenges.